Method for polishing diamond wafers

ABSTRACT

A method for polishing diamond wafers. At least a diamond wafer is mounted onto a ceramic plate with wax disposed therebetween and is pressed onto the ceramic plate. The ceramic plate is fixed on a first transmission device of a polishing machine by a vacuum. The ceramic plate is driven by the first transmission device to rotate and move towards a metal disc fixed on a second transmission device driven to rotate unmoved such that the diamond wafer on the ceramic plate is being polished by the metal disc. The method for polishing diamond wafers of the present invention uses the metal disc so as to reduce cost, time and improve polishing efficiency.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method for polishing diamond wafers and, more particularly, to a method using a metal disc so as to polish diamond wafers.

2. Description of the Prior Art

In semiconductor manufacturing, surface flatness has become crucial because of the demand for high integrity of an integrated circuit (IC). More specifically, chemical mechanical polishing (CMP) is one of the most important techniques used for surface flatness of semiconductor wafers.

Please refer to FIG. 1, which is a schematic diagram illustrating a conventional CMP process. In FIG. 1, a polishing head 10 uses the atmosphere pressure to suck a wafer 12 on the backside such that the surface of the wafer 12 faces a polishing pad 14 and is polished. In order to avoid the polishing head 10 to contact the wafer 12 leading to the damage of the wafer 12, a buffer pad 16 comprising a plurality of vent holes is disposed between the polishing head 10 and the wafer 12. Moreover, a slurry 20 ejected from a slurry supply 18 is used when the wafer 12 is being polished.

However, for diamond wafers, i.e., wafers with a diamond film on the surface, conventional CMP is not capable of polishing the diamond film due to its physical and chemical properties. Therefore, diamond wafers with surface roughness of several micrometers are not applicable to compact micro-electronic devices. Even thought there have been some studies and research reports on surface flatness of diamond films, an effective method for polishing diamond wafers is still yet to come when manufacturing efficiency, cost and time are taken into account.

Therefore, there is need in providing a method for polishing diamond wafers so as to overcome the aforementioned problems.

SUMMARY OF THE INVENTION

It is the primary object of the present invention to provide a method for polishing diamond wafers, using a first transmission device to drive a diamond wafer moving towards a rotating metal disc such that the metal disc polishes the surface of the diamond wafer.

It is the secondary object of the present invention to provide a method for polishing diamond wafers so as to reduce cost and time.

In order to achieve the foregoing objects, the present invention provides a method for polishing diamond wafers, comprising steps of: providing at least a diamond wafer fixed on a plate; fixing the plate onto a first transmission device of a polishing machine such that a surface of the diamond wafer faces a metal disc fixed onto a second transmission device of the polishing machine; and rotating the metal disc driven by the second transmission device and rotating the plate driven by the first transmission device to move towards the metal disc so as to polish the diamond wafer fixed on the plate.

Other and further features, advantages and benefits of the invention will become apparent in the following description taken in conjunction with the following drawings. It is to be understood that the foregoing general description and following detailed description are exemplary and explanatory but are not to be restrictive of the invention. The accompanying drawings are incorporated in and constitute a part of this application and, together with the description, serve to explain the principles of the invention in general terms.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, spirits and advantages of the preferred embodiment of the present invention will be readily understood by the accompanying drawings and detailed descriptions:

FIG. 1 is a schematic diagram illustrating a conventional chemical mechanical polishing (CMP) process;

FIG. 2 is a schematic diagram illustrating the step of coating wax on the diamond wafers in the present invention; and

FIG. 3 is a schematic diagram illustrating a method for polishing diamond wafers in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention providing a method for polishing diamond wafers can be exemplified by the preferred embodiment as described hereinafter.

As shown in FIG. 2, the method for polishing diamond wafers according to the present invention starts with providing at least a diamond wafer 30 on a plate 32 with wax disposed therebetween and fixing the diamond wafer 30 onto the plate 32 using a pressure. Referring to FIG. 3, the plate 32 mounted with the diamond wafer 30 is fixed on a first transmission device 36 of a polishing machine 34 using a vacuum. The first transmission device 36 is controlled by a control unit 38 so as to drive the plate 32 and the diamond wafer 30 to rotate, move back and forth and move perpendicularly to a direction towards a metal disc 40 driven by a second transmission device 42 to rotate unmoved. The control unit 38 has input polishing parameters so as to control the first transmission device 36 and the second transmission device 42 for determining the wafer thickness and polishing time. Therefore, the diamond wafer 30 on the plate 32 is driven by the first transmission device 36 to move towards the metal disc 40 so as to polish the diamond wafer 30. After a certain period of polishing time, the control unit 38 controls the first transmission device 36 to drive the diamond wafer 30 to move backwards, rotates and move perpendicularly to a direction towards the metal disc 40. The first transmission device 36 repeats the aforementioned operation such that the metal disc 40 polishes the diamond wafer 30 until a determined of diamond wafer thickness is obtained.

Furthermore, as shown in FIG. 3, the polishing machine 34 comprises at least a cooling liquid outlet 44 for ejecting a cooling liquid so as to rinse and cool down the metal disc 40 and the diamond wafer 30. The metal disc 40 is made of steel or an alloy thereof. The plate 32 is made of ceramic of plastic materials. In addition to wax used as an adhesive between the diamond wafer 30 and the plate 32, other adhesives or methods can be used to fix the diamond wafer 30 onto the plate 32. In order to improve flexibility in using the present invention, the control unit 38 controls the first transmission device 36 to stay unmoved and the second transmission device 42 to drive the metal disc 40 to rotate and move towards the diamond wafer 30 when the diamond wafer 30 is being polished. Similarly, the control unit 38 controls the first transmission device 36 and the second transmission device 42 to rotate, move back and forth and move perpendicularly to the direction towards each other according to the input polishing parameters.

According to the above discussion, the present invention discloses a method for polishing diamond wafers using a first transmission device to drive a diamond wafer moving towards a rotating metal disc such that the metal disc polishes the surface of the diamond wafer. Therefore, the present invention has been examined to be new, non-obvious and useful.

Although this invention has been disclosed and illustrated with reference to particular embodiments, the principles involved are susceptible for use in numerous other embodiments that will be apparent to persons skilled in the art. This invention is, therefore, to be limited only as indicated by the scope of the appended claims. 

1. A method for polishing diamond wafers, comprising steps of: providing at least a diamond wafer fixed on a plate; fixing said plate onto a first transmission device of a polishing machine such that a surface of said diamond wafer faces a metal disc fixed onto a second transmission device of said polishing machine; and rotating said metal disc driven by said second transmission device and rotating said plate driven by said first transmission device to move towards said metal disc so as to polish said diamond wafer fixed on said plate.
 2. The method as recited in claim 1, wherein said plate is a ceramic plate.
 3. The method as recited in claim 1, wherein said diamond wafer is mounted on said plate with wax disposed therebetween and is pressed to be fixed on said plate.
 4. The method as recited in claim 1, wherein said plate is fixed on said transmission device by a vacuum.
 5. The method as recited in claim 1, wherein said metal disc is made of steel or an alloy thereof.
 6. The method as recited in claim 1, wherein said polishing machine comprising a control unit with input polishing parameters so as to control said first transmission device and said second transmission device for determining the wafer thickness and polishing time.
 7. The method as recited in claim 1, wherein said metal disc is driven and controlled by said second transmission device to rotate unmoved and said plate is driven and controlled by said first transmission device to rotate moving towards said metal disc so as to polish said diamond wafer.
 8. The method as recited in claim 1, wherein said plate is driven and controlled by said first transmission device to rotate moving towards said metal disc for a first interval of time and moving away from said metal disc for a second interval of time.
 9. The method as recited in claim 1, wherein said plate is driven and controlled by said first transmission device to repeat moving towards said metal disc and moving away from said metal disc.
 10. The method as recited in claim 1, wherein said plate is driven and controlled by said first transmission device to move towards said metal disc and move perpendicularly to a direction towards said metal disc.
 11. The method as recited in claim 1, wherein said plate is driven and controlled by said first transmission device to rotate and move towards said metal disc.
 12. The method as recited in claim 1, wherein said metal disc is driven by said second transmission device controlled by said control unit to move back and forth and move perpendicularly to a direction towards said plate.
 13. The method as recited in claim 1, wherein said polishing machine comprises at least a cooling liquid outlet for ejecting a cooling liquid so as to rinse and cool down said metal disc and said diamond wafer. 